During the Christmas season, strings of electric lights are frequently used for decoration. These strings of electric lights can be subjected to various forces and environmental conditions that can degrade a typical wire. For example, the strings of electric lights may be suspended from rooflines, wrapped around trees, or affixed to other decorative objects. When used for these purposes, electric light strings can be subjected to tensile forces carried in part by the wires in the electric light strings. For this reason, in some cases, it can be desirable or required for the wires to meet certain tensile strength requirements. For example, light strings may be pulled taut while being attached to a roofline. Light strings may also be used to suspend other objects, such as Christmas decorations. Because electric light strings carry electricity, electric light strings need to be able to withstand forces in tension without failing. If a string fails, a customer may be disappointed by the broken light string and may be reluctant to buy that brand of light string in the future. Further, if a string fails, injury can occur due to falling objects or exposure of electric wiring. Wiring used in electric light strings can also be required to meet certain regulatory standards for mechanical or electrical performance to ensure consumer safety. For example, wiring in electric light strings can be required to meet UL standards in the United States. Some of these standards may relate to tensile strength, flammability, melting points, and cold temperature bending, for example.
Electric light strings can comprise a plurality of lamp assemblies connected by one or more wires, and an electrical connector or power plug. Wiring used in strings of electric lights can include an electrical conductor surrounded by an insulator jacket. The electrical conductor can comprise multiple strands of conductive material, such as copper. For example, an ordinary string of incandescent lights can be constructed using #22 AWG wire that contains 16 individual copper strands, and is covered by an insulator jacket made of plastic, such as polyvinyl chloride (PVC).
One way to increase the tensile strength of a wire is to use a thicker wire, such as #20 AWG wiring, or thicker. By doing so, the additional conductive strands or thicker conductive strands can increase the mechanical strength of the wire. However, the conductive materials used in conductive strands are sometimes too expensive for such an approach to be cost effective. For example, common conductors such as copper or aluminum are commodity materials that can be very expensive. Alternatively, multiple wires can be used to connect lamp assemblies. In some electric light strings, twisted pairs of wires are used to increase the tensile strength of the wire. As with the use of thicker wire, this approach can also sometimes be too expensive.
What is needed, therefore, is a reinforced wire that provides improved tensile strength to prevent breakage and that can be manufactured at relatively low cost. Some embodiments of the present invention address this need as well as other needs that will become apparent upon reading the description below in conjunction with the drawings.